Review Question - QID 4807

This patient has sustained a displaced extension-type supracondylar fracture. The most commonly affected nerve in this setting is the anterior interosseous nerve (AIN). This will affect thumb IP flexion.

The most common neurapraxia after pediatric extension-type supracondylar fractures involve the AIN. It supplies the FPL (thumb IP flexion), the pronator quadratus, and the FDP of the index/long fingers. Subsequently, patients are often unable to make an “a-ok” sign. Most of these neuropraxias resolve without complication. The ulnar nerve is most commonly implicated with flexion-type supracondylar fractures.

Abzug et al. review management of supracondylar fractures. They note that the AIN is most commonly injured nerve in extension type supracondylar fractures. They note that nerve injuries often resolve within 6-12 weeks.

Babal et al. completed a meta-analysis to determine the risk of neurapraxia associated with pediatric supracondylar fractures. The rate of traumatic neurapraxia was 11.4% amongst 5000 patients. The AIN was affected 34.1% of the time. AIN neurapraxia was most common in extension type injuries.

Figures A and B show an AP and lateral radiographs of a displaced pediatric supracondylar fracture

Incorrect Answers
Answer 1: The intrinsics are innervated by the ulnar nerve which is implicated in flexion-type supracondylar fractures
Answer 2: The wrist extensors are innervated by the radial nerve. The radial nerve is not affected as commonly as the AIN
Answers 3, 5: The digital extensors and the thumb extensors are innervated by the posterior interosseous nerve (PIN) which is not affected as commonly as the AIN